1. Technical Field
The present invention relates to a light source device and a projector.
2. Related Art
There have been known a light source device, which excites a phosphor with light emitted from a plurality of semiconductor lasers, and uses the fluorescence emitted from the phosphor thus excited, and a projector using the light source device (see, e.g., JP-A-2012-137744).
In the light source device, the light emitted from a solid-state light source unit is split by a polarization splitting mirror, one light thus split is guided to a phosphor layer as excitation light, and the other light thus split and the light obtained from the phosphor layer are combined with each other to obtain illumination light. Further, by adjusting the polarization state of the light entering the polarization splitting mirror using a wave plate disposed on the light path between the solid-state light source unit and the polarization splitting mirror, the desired light with the color balance adjusted is generated.
Incidentally, in the light source device described above, the excitation light emitted from the solid-state light source unit enters an optical element disposed in an anterior stage of the polarization splitting mirror, and thus, the optical element is heated and is expanded. Then, birefringence occurs in the optical element due to the photoelastic effect, and the polarization state of the excitation light is disturbed. Therefore, there is a possibility that it is unachievable to split the light emitted from the solid-state light source unit using the polarization splitting mirror at a predetermined proportion, and the desired light cannot be generated.